1. Field of the Invention
The present invention relates generally to wireless communication networks, and more particularly to error-checking of data transmissions.
2. Description of the Background Art
Spread spectrum wireless communication systems use a type of modulation that spreads data transmission across an available frequency band in excess of the minimum bandwidth required to send the information. Direct Sequence Spread Spectrum (“DSSS”) is the most widely recognized form of spread spectrum. One of the unique benefits of DSSS techniques is that multiple data transmissions—being distinguishable by uniquely assigned codes—can share the same bandwidth (i.e., can be transmitted over the same frequency at the same time). An application of this technology—Code Division Multiple Access (“CDMA”)—is prevalent in the cellular telephone industry.
DSSS systems incur random transmission errors caused by, among other things, noise and interference. As a result, DSSS systems typically incorporate error-correction techniques—such as Forward Error Correction (“FEC”) techniques—for detecting and correcting transmission errors. One of the most common FEC techniques uses the Viterbi error-correction algorithm well known in the art (hereafter “Viterbi error-checking”). In Viterbi error-checking, a convolutional encoder (hereafter “Viterbi encoder”) in the transmitting system encodes the input data stream into Viterbi error states. The Viterbi error states are then decoded in the receiving system using a Viterbi decoder for detection and correction of transmission errors.